Place:

Sedgemoor
Somerset

In 1870-72, John Marius Wilson's Imperial Gazetteer of England and Wales
described Sedgemoor like this:

SEDGEMOOR, a marshy tract in the centre of Somerset; 5 miles S E of Bridgewater. It was the scene of the Duke of Monmouth's defeat in 1685; was also the place where a base line of the Trigonometrical survey was measured; and is intersected by dykes, which contributed much to the discomfiture of Monmouth's troops.